High resolution mass spectrometry will be employed in studying biomedically important compounds, stressing the new technique of fast atom bombardment mass spectrometry (FABMS). A high field mass spectrometer will be modified to observe ions to m/z 10,000 at maximum accelerating potential (8KV). A variety of ion guns as well as postanalyzer acceleration will be employed to enhance sensitivity. Several matrices will be studied to enhance FAB ion production. Mass markers will be prepared to facilitate computerized data collection and accurate mass measurements of both positive and negative ions, and optimization of high resolution measurements will be studied in ion sources of different designs. Collisional activation will be employed to enhance FAB-induced fragmentation. A high performance liquid chromatograph will be coupled to a FAB mass spectrometer by a modified moving belt apparatus. Compounds to be studied by these techniques include involatile or thermally unstable antibiotics (especially peptides and polyenes), antiviral, antitumor and antimicrobial marine natural products, other peptides (enzymic digests of proteins, fluorogenic peptides, peptide derivatives of drugs and suicide inhibitors), polynucleotides, glycolipids, including gangliosides, coenzymes, terpene pyrophosphates, modified porphyrins, organometallic analogs of metalloenzymes, carcinogenic metabolites, organic compounds with hypervalent atoms, sulfonium salts, and metal carbonyls.